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Social status changes hyenas’ epigenetics

An animal’s position in hierarchical hyena packs influences her gene expression.

For a spotted hyena on the Serengeti, social status is everything. Clans adhere to a strict hierarchy of dominance among adult females. Now, a group of researchers has found social status is more than superficial; it stretches into the animals’ DNA (Commun. Biol. 2024, DOI: 10.1038/s42003-024-05926-y).

Many traditional methods for collecting DNA are too invasive for wild hyena populations, says lead researcher Alexandra Weyrich from the German Centre for Integrative Biodiversity Research, Halle-Jena-Leipzig. “So, we sample the feces.”

In collaboration with Weyrich, researchers from the Serengeti Hyena Project—who know each individual animal by sight—scooped the poop for later analysis.

“What we found is quite stunning,” says Weyrich: there is a distinct correlation between social status and DNA methylation. Adding methyl groups to certain regions of DNA changes how those regions are transcribed and can act like a genetic on/off switch.

Forty-four genes are associated with the 147 differently methylated regions they found, says Weyrich. Some of these genes regulate energy conversion and appear more methylated in low-status females. This indicates that the animals are processing energy differently than their social superiors, says Weyrich, perhaps because low-ranking hyenas are forced to travel farther for resources.

“I think the data they found was quite solid and interesting,” says Michael Skinner, an epigeneticist at Washington State University. To him, this is another study demonstrating that epigenetic processes control most biological phenomena.

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Genes identified that allow bacteria to thrive despite toxic heavy metal in soil

Some soil bacteria can acquire sets of genes that enable them to pump the heavy metal nickel out of their systems, a study has found. This enables the bacteria to not only thrive in otherwise toxic soils but help plants grow there as well.

A Washington State University-led research team pinpointed a set of genes in wild soil bacteria that allows them to do this in serpentine soils which have naturally high concentrations of toxic nickel. The genetic discovery, detailed in the journal Proceedings of the National Academies of Sciences, could help inform future bioremediation efforts that seek to return plants to polluted soils.

“We can say with certainty that these are the genes that are letting the bacteria survive the heavy metal exposure because if we take them away, they die. If we add them to a new bacterium that was sensitive to the heavy metal, all of the sudden it’s resistant,” said Stephanie Porter, the study’s senior author and a WSU evolutionary ecologist.

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Meet the ice worm, one of the most mysterious creatures in the world

When Peter Wimberger of the University of Puget Sound was first told about ice worms, he thought that his colleagues were pranking him. Imagine his surprise when he learned that not only are these creatures real, they are full of mysteries that if solved, could help answer one of the biggest questions in science.

There are millions of these animals across the world and yet despite their abundance, they have barely been studied, with scientists treating them as a mere curiosity. Scott Hotaling, a glacier biologist [at Utah State University and a former postdoctoral researcher at] Washington State University, and his colleague Peter Wimberger have been studying ice worms for several years.

“There are more mysteries than there are solved things with ice worms”, says Hotaling.

Unlike humans, who lose energy when they are in a cold environment, ice worms thrive in the cold and their energy levels go up when they are subjected to low temperatures. They live comfortably at 32 degrees Fahrenheit (0 degrees Celsius), but if temperatures dip slightly below that, they die.

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Toxicant Exposures Show Health Effects Across Generations

While exposure to a single substance like DDT has been shown to create inherited disease susceptibility, a recent study in animals found exposure to multiple different toxicants across generations can amplify those health problems.

In the study, published in the journal Environmental Epigenetics, the researchers exposed an initial generation of pregnant rats to a common fungicide, then their progeny to jet fuel, and the following generation to DDT. When those rats were then bred out to a fifth unexposed generation, the incidence of obesity as well as kidney and prostate diseases in those animals were compounded, rising by as much as 70%.

The researchers also found that their epigenetics, molecular processes independent of DNA that influence gene expression, were also greatly altered.

“We looked at multiple-generation exposures because these types of things are going on routinely, and previous research has only looked at single exposures,” says Michael Skinner, a Washington State University biology professor and the study’s corresponding author. “We found that if multiple generations get different exposures, then eventually there’s an amplification or compounded effect on some diseases.”

The study did show that for other diseases, those associated with the ovaries and the testes, the incidence rose in the first generation of progeny but appeared to plateau with the additional generational exposures.

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High maternal cortisol levels linked to unexpected birth problems

A snippet of hair can reveal a pregnant person’s stress level and may one day help warn of unexpected birth problems, a study indicates.

Washington State University researchers measured the stress hormone cortisol in hair samples of 53 women in their third trimester. Of that group, 13 women who had elevated cortisol levels later experienced unpredicted birth complications, such as an early birth or hemorrhaging.

While more research is needed with larger groups, this preliminary finding could eventually lead to a non-invasive way to identify those at risk for such complications. The researchers reported their findings in the journal Psychoneuroendocrinology.

“There was otherwise nothing about these women that would suggest a disease or anything else complicating the pregnancy. This confirmed some hypotheses that levels of stress, related specifically to cortisol levels, might be associated with adverse birth outcomes,” said Erica Crespi, a WSU developmental biologist and study’s corresponding author.

As part of the study, the participants all answered survey questions about their levels of psychological distress in addition to having cortisol measurements taken in the third trimester of pregnancy and after they gave birth. The women who experienced unexpected birth complications had elevated cortisol concentrations in their hair, a measure that indicates the stress hormone’s circulating levels in the body during the three months prior to collection.

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